This invention relates to a whole house fan, and, in particular, to a direct drive whole house fan wherein the fan motor is mounted on top of a single joist.
The use of whole house fans to help keep houses cool during summer months has long been known. The advantages to using whole house fans is set out in detail in U.S. Pat. No. 4,501,194 to Brown assigned to Emerson Electric Co.
Installation of whole house fans, such that a home owner or a "do-it-yourselfer" could install them, has only recently become popular. In many prior whole house fans it was necessary to cut ceiling joists and to form a plenum box by nailing header plates between the uncut joists and the ends of the cut joists. This involves major carpentry work which, depending upon the structure of the roof, could weaken the roof.
To eliminate this problem, whole-house fans were introduced which included a frame mountable on the tops of adjacent ceiling joists over an opening in the ceiling. A venturi was carried by the frame and a skirt depended downwardly from the venturi and fit around the uncut joists to form a plenum box. The frame was mounted on the joists and the motor was mounted on crossbars of the frame beneath the venturi. The motor was thus mounted between and supported by two joists and a large frame. Importantly, these "easy-to-install" whole house fans did not require cutting of ceiling joists when the opening was made in the ceiling. The above-mentioned patent to Brown and U.S. Pat. No. 4,385,550 to Steiner et al, also co-assigned to Emerson Electric Co., are examples of such "easy-to-install" whole house fans.
In order to make the installation of whole house ceiling fans even easier and to reduce the cost of such fans, it was desirable to make the motor and fan directly mountable to a middle joist centered on the ceiling opening and to make the venturi separately mountable directly to the middle joist. However, it was feared that if the direct drive motor and fan were mounted to a single joist, the fan would be unstable and would wobble on the joist. This in turn would cause the joist to also wobble or twist and could result in damage to the joist or ceiling of the house and would result in objectionable noise.